JP7403289B2 - Positive electrode active material composite for lithium ion secondary battery and method for manufacturing the same - Google Patents

Description

The present invention relates to a positive electrode active material composite for a lithium ion secondary battery and a method for manufacturing the same, for obtaining a lithium ion secondary battery with excellent discharge capacity and rate characteristics.

Lithium composite oxides are used as positive electrode active materials that can construct high-power and high-capacity lithium ion secondary batteries, but lithium ion secondary batteries that use such lithium composite oxides as positive electrode active materials usually As charge and discharge cycles are repeated, the capacity decreases, and especially when used for a long period of time, there is a possibility that the capacity decrease of the battery becomes significant. The reason for this is thought to be that the crystal structure of the lithium composite oxide is more likely to be destroyed due to elution of transition metal components into the electrolyte during charging. Further, if the crystal structure of the lithium composite oxide is destroyed, the transition metal component of the lithium composite oxide will be eluted into the surrounding electrolyte, which may reduce thermal stability and impair safety.

Under these circumstances, various positive electrode active materials have been developed in order to realize lithium ion secondary batteries with better battery characteristics. For _{example ,} in Patent _{Document 1} , _{Li 1+} A positive electrode active material for a secondary battery in which lithium metal phosphate nanoparticles represented by _x M' _x M'' _2-x (PO ₄ ) ₃ (M' and M'' are predetermined metals) are arranged is The invention is intended to improve high capacity, thermal safety, and high-temperature life characteristics in secondary batteries. Further, Patent Document 2 discloses a positive electrode active material comprising a coating layer containing a solid electrolyte containing Li, La, Al, Zr, etc. on the surface of active material particles containing a lithium composite oxide mainly composed of nickel. Materials have been disclosed that attempt to improve the cycle characteristics of non-aqueous secondary batteries while maintaining their discharge capacity.
In this manner, in both documents, various battery characteristics are improved by using a positive electrode active material in which the surface of so-called lithium composite oxide particles is coated with lithium ion solid electrolyte particles.

Special Publication No. 2018-517243 JP 2019-3786 Publication

However, the inventors' studies have revealed that even with the positive electrode active material described in the above patent document, there is still room for further improvement in order to sufficiently increase the discharge capacity and rate characteristics when forming a lithium ion secondary battery. It turns out that there is.

Therefore, an object of the present invention is to provide a positive electrode active material composite for a lithium ion secondary battery that can realize a lithium ion secondary battery having good discharge capacity and rate characteristics while using lithium composite oxide particles. It's about doing.

Therefore, as a result of intensive studies to solve the above problems, the present inventors found that specific lithium positive electrode active material particles (B) are supported on the surface of specific lithium composite oxide secondary particles (A). In addition, in the case of a positive electrode active material composite for a lithium ion secondary battery in which a lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B), the resulting lithium ion secondary battery It has been found that it is possible to effectively improve discharge capacity and rate characteristics.

Therefore, the present invention provides the following formula (1) or formula (2):
_LiNia Co _b Mn _c M ¹ _w O ₂ ...(1)
(In formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Represents one or more elements selected from Bi and Ge. a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, Indicates a number that satisfies 0≦w≦0.3 and 3a+3b+3c+(valence of ^M1 )×w=3.)
LiNi _d Co _e Al _f M ² _x O ₂ ...(2)
(In formula (2), ^M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and Represents one or more elements selected from Ge. d, e, f, x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ Indicates a number that satisfies x≦0.3 and 3d+3e+3f+(valence of ^M2 )×x=3.)
On the surface of lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (3), formula (4), formula (5), or formula (6):
^LiM3gCohO2 _{... (} 3 ₎
(In formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) In, g and h indicate numbers that satisfy 0≦g≦0.1, 0<h≦1, and (valence of M ³ )×g+3h=3.)
LiM ⁴ _i Mn _j O ₄ ...(4)
(In formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In formula (4), i and j represent numbers satisfying 0≦i≦0.1, 0<j≦2, and (valence of ^M4 )×i+(valence of Mn)×j=7 .)
LiNik _{Mn 1-k} O ₄ ...(5)
(In formula (5), k represents a number satisfying 0.3≦k≦0.7.)
_Li2MnO3 ^-LiM6O2 _... ( ₆ )
(In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. (Indicates one or more elements selected from.)
A positive electrode active for a lithium ion secondary battery, in which lithium positive electrode active material particles (B) represented by: A substance complex (D) is provided.

Further, the present invention provides the following steps (I) to (III):
(I) After preparing a slurry (a-1) containing the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C) and having a solid content concentration of 20% to 65% by mass, hot air The ratio (G/S) of supply amount G (L/min) of slurry (a-1) to supply amount S (L/min) of slurry (a-1) is 500 to 10,000 to obtain granules (a). The process of obtaining
(II) The obtained granules (a) are fired at 500°C to 800°C for 10 minutes to 3 hours, and the lithium positive electrode active material particles (B ), and (III) obtaining a pre-granulated product (b) with a porosity of 45% to 80% by volume, and (III) obtaining a pre-granulated product (b) and lithium composite oxide secondary particles (A ) while applying compressive force and shearing force to crush the pre-granulated material (b), and produce lithium positive electrode active material particles (B) having a lithium-based solid electrolyte (C) supported on the surface. ) and lithium composite oxide secondary particles (A) are provided.

According to the positive electrode active material composite for a lithium ion secondary battery of the present invention, the lithium positive electrode active material particles carrying a lithium-based solid electrolyte are effectively supported on the surface of the lithium composite oxide secondary particles. A lithium ion secondary battery having good discharge capacity and rate characteristics can be realized.

The present invention will be explained in detail below.
The positive electrode active material composite (D) for lithium ion secondary batteries of the present invention has the following formula (1) or formula (2):
_LiNia Co _b Mn _c M ¹ _w O ₂ ...(1)
(In formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Represents one or more elements selected from Bi and Ge. a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, Indicates a number that satisfies 0≦w≦0.3 and 3a+3b+3c+(valence of ^M1 )×w=3.)
LiNi _d Co _e Al _f M ² _x O ₂ ...(2)
(In formula (2), ^M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and Represents one or more elements selected from Ge. d, e, f, x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ Indicates a number that satisfies x≦0.3 and 3d+3e+3f+(valence of ^M2 )×x=3.)
On the surface of lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (3), formula (4), formula (5), or formula (6):
^LiM3gCohO2 _{... (} 3 ₎
(In formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) In, g and h indicate numbers that satisfy 0≦g≦0.1, 0<h≦1, and (valence of M ³ )×g+3h=3.)
LiM ⁴ _i Mn _j O ₄ ...(4)
(In formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In formula (4), i and j represent numbers satisfying 0≦i≦0.1, 0<j≦2, and (valence of ^M4 )×i+(valence of Mn)×j=7 .)
LiNik _{Mn 1-k} O ₄ ...(5)
(In formula (5), k represents a number satisfying 0.3≦k≦0.7.)
_Li2MnO3 ^-LiM6O2 _... ( ₆ )
(In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. (Indicates one or more elements selected from.)
The lithium positive electrode active material particles (B) represented by the following formula are supported, and a lithium-based solid electrolyte (C) is supported on the surface of the lithium positive electrode active material particles (B).

The lithium composite oxide secondary particles (A) constituting the positive electrode active material composite (D) for lithium ion secondary batteries of the present invention are expressed by the following formula (1) or formula (2):
_LiNia Co _b Mn _c M ¹ _w O ₂ ...(1)
(In formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Represents one or more elements selected from Bi and Ge. a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, Indicates a number that satisfies 0≦w≦0.3 and 3a+3b+3c+(valence of ^M1 )×w=3.)
LiNi _d Co _e Al _f M ² _x O ₂ ...(2)
(In formula (2), ^M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and Represents one or more elements selected from Ge. d, e, f, x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ Indicates a number that satisfies x≦0.3 and 3d+3e+3f+(valence of ^M2 )×x=3.)
These are secondary particles made of lithium composite oxide particles represented by , and are particles having a layered rock salt structure.

Lithium composite oxide particles represented by the above formula (1) (so-called Li-Ni-Co-Mn oxide, hereinafter referred to as "NCM-based composite oxide") and the lithium composite oxide particles represented by the above formula (2) Lithium composite oxide particles (so-called Li-Ni-Co-Al oxides, hereinafter referred to as "NCA-based composite oxides") are also particles with a layered rock salt structure, and by agglomeration, lithium composite oxide form secondary particles (A). Therefore, the secondary particles are also referred to as "NCM-based composite oxide secondary particles (A)", "NCA-based composite oxide secondary particles (A)", etc.

The NCM-based composite oxide particles represented by the above formula (1) form lithium composite oxide secondary particles (A). M ¹ in formula (1) is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Indicates one or more elements selected from Bi and Ge.
In addition, a, b, c, and w in the above formula (1) are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, 0≦w≦0.3, And it is a number that satisfies 3a+3b+3c+(valence of ^M1 )×w=3.

In the NCM-based composite oxide particles represented by the above formula (1), Ni, Co, and Mn are known to have excellent electronic conductivity and contribute to battery capacity and output characteristics. Moreover, from the viewpoint of cycle characteristics, it is preferable that a part of the transition element is replaced by another metal element M ¹ . By being substituted with these metal elements M ¹ , the crystal structure of the NCM-based composite oxide particles represented by formula (1) is stabilized, so even if charging and discharging are repeated, destruction of the crystal structure can be suppressed. It is believed that excellent cycle characteristics can be achieved.
Specifically, the NCM-based composite oxide particles represented by the above formula (1) include, for example, LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.2 Co _0.4 Mn _0.4 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ , or LiNi _0.33 Co _0.31 Mn _0.33 Zn _0.03 O ₂ . Among them, LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 Particles consisting of _O2 are preferred.

Furthermore, two or more types of NCM-based composite oxide particles represented by the above formula (1) having different compositions have a core-shell structure of lithium composite oxide particles having a core part (interior) and a shell part (surface layer part). secondary particles (A) (NCM-based composite oxide secondary particles (A)) may be formed.

By forming the NCM-based composite oxide secondary particles (A) formed with this core-shell structure, NCM-based composite oxide particles with a high Ni concentration that are easily eluted into the electrolytic solution are placed in the core part, and electrolytic Since NCM-based composite oxide particles with a low Ni concentration can be placed in the shell portion that comes into contact with the liquid, it is possible to further suppress deterioration of cycle characteristics and ensure safety. At this time, the core portion may be composed of one phase, or may be composed of two or more phases having different compositions. As an embodiment in which the core part is composed of two or more phases, it may be a structure in which a plurality of phases are laminated in concentric circles, or a structure in which the composition changes transitionally from the surface of the core part toward the center part. good.
Further, the shell portion may be formed outside the core portion, and may be formed of one phase like the core portion, or may be formed of two or more phases having different compositions.

Specifically, the NCM-based composite oxide secondary particles (A) formed by forming a core-shell structure by two or more types of NCM-based composite oxide particles having different compositions include (core part) - (shell part). For example, (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ )-(LiNi _0.2 Co _0.4 Mn _0.4 O ₂ ), (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ )-(LiNi _0.33 Co _0.33 Mn _0.34 O ₂ ) or Examples include particles consisting of (LiNi _0.8 Co _0.1 Mn _0.1 O ₂ )-(LiNi _0.33 Co _0.31 Mn _0.33 Mg _0.03 O ₂ ).

Furthermore, the NCM-based composite oxide particles represented by the above formula (1) may be coated with a metal oxide, a metal fluoride, or a metal phosphate. By coating the NCM-based composite oxide particles with these metal oxides, metal fluorides, or metal phosphates, metal components (Ni, Mn, Co, M ¹ ) from the NCM-based composite oxide particles are added to the electrolyte. The elution of can be suppressed. Such coatings include _CeO2 , _SiO2 , _MgO , _Al2O3 , ZrO2, _{TiO2 ,} ZnO, _RuO2 , _{SnO2 ,} CoO, _Nb2O5 , CuO _{, V2O5} , _MoO3 , One or more selected from La ₂ O ₃ , WO ₃ , AlF ₃ , NiF ₂ , MgF ₂ , Li ₃ PO ₄ , Li ₄ P ₂ O ₇ , LiPO ₃ , Li ₂ PO ₃ F, and LiPO ₂ F ₂ Two or more types or a composite thereof can be used.

The average particle diameter of the NCM-based composite oxide particles represented by the above formula (1) as primary particles is preferably 500 nm or less, more preferably 300 nm or less. In this way, by setting the average particle diameter of the NCM-based composite oxide particles as primary particles to at least 500 nm or less, it is possible to suppress the amount of expansion and contraction of the primary particles due to insertion and desorption of lithium ions, Particle cracking can be effectively prevented. Note that the lower limit of the average particle diameter of the primary particles is not particularly limited, but from the viewpoint of handling, it is preferably 50 nm or more.
Here, the average particle size means the average value of the measured values of the particle size (long axis length) of several dozen particles in SEM or TEM electron microscope observation, and it has the same meaning in the following explanation. be.

Further, the average particle size of the NCM-based composite oxide secondary particles (A) formed by agglomeration of the primary particles is preferably 25 μm or less, more preferably 20 μm or less. When the average particle size of such secondary particles is 25 μm or less, a battery with excellent cycle characteristics can be obtained. Note that the lower limit of the average particle diameter of the secondary particles is not particularly limited, but from the viewpoint of handling, it is preferably 1 μm or more, and more preferably 5 μm or more.
Note that in this specification, NCM-based composite oxide secondary particles (A) include only primary particles forming secondary particles, and include lithium positive electrode active material particles (B) and lithium-based solid electrolyte (C). Does not include.

When the NCM-based composite oxide particles represented by the above formula (1) form a core-shell structure in the NCM-based composite oxide secondary particles (A), the average as the primary particles forming the core part The particle size is preferably 50 nm to 500 nm, more preferably 50 nm to 300 nm. The average particle diameter of the core portion formed by agglomeration of the primary particles is preferably 1 μm to 25 μm, more preferably 1 μm to 20 μm.
Further, the average particle diameter of the NCM-based composite oxide particles as primary particles constituting the shell portion covering the surface of the core portion is preferably 50 nm to 500 nm, more preferably 50 nm to 300 nm, and The layer thickness of the shell portion formed by agglomeration of primary particles is preferably 0.1 μm to 5 μm, more preferably 0.1 μm to 2.5 μm.

The internal porosity of the NCM-based composite oxide secondary particles (A) consisting of the NCM-based composite oxide particles represented by the above formula (1) is determined by the expansion of the NCM-based composite oxide due to the insertion of lithium ions. From the viewpoint of allowing it within the internal voids of the particles, it is preferably 4% to 12% by volume, more preferably 5% to 10% by volume, based on 100% by volume of the NCM-based composite oxide secondary particles (A).
By having such an average particle size and internal porosity, on the surface of the NCM-based composite oxide secondary particles (A) consisting of the NCM-based composite oxide particles represented by the above formula (1), the NCM-based composite oxide The particles and the lithium positive electrode active material particles (B) are composited, and the lithium positive electrode active material particles (B) are supported so as to cover the surface of the NCM-based composite oxide secondary particles (A). Therefore, while effectively suppressing the elution of metal components (Ni, Co, Mn, M ¹ ) contained in the NCM-based composite oxide particles, the discharge capacity and rate characteristics of the resulting lithium ion secondary battery can be sufficiently maintained. can be increased to

The NCA-based composite oxide particles represented by the above formula (2) form lithium composite oxide secondary particles (A) similarly to the above-mentioned NCM-based composite oxide particles. M ² in formula (2) is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and Indicates one or more elements selected from Ge.
In addition, d, e, f, and x in the above formula (2) are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦x≦0.3, And it is a number that satisfies 3d+3e+3f+(valence of M ² )×x=3.

The NCA-based composite oxide particles represented by the above formula (2) are even more excellent in battery capacity and output characteristics than the NCM-based composite oxide particles represented by the formula (1). In addition, due to the Al content, deterioration due to moisture in the atmosphere is less likely to occur, and it is also excellent in safety.
Specifically, the NCA-based composite oxide particles represented by the above formula (2) include, for example, LiNi _0.33 Co _0.33 Al _0.34 O ₂ , LiNi _0.8 Co _0.1 Al _0.1 O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 Examples include particles made of O ₂ , LiNi _0.8 Co _0.15 Al _0.03 Zn _0.03 O ₂ , and the like. Among these, particles made of LiNi _0.8 Co _0.15 Al _0.03 Mg _0.03 O ₂ are preferred.

Furthermore, the NCA-based composite oxide particles represented by the above formula (2) may be coated with a metal oxide, a metal fluoride, or a metal phosphate. By coating the NCA-based composite oxide particles with these metal oxides, metal fluorides, or metal phosphates, metal components (Ni, Al, Co, M ² ) from the NCA-based composite oxide particles are added to the electrolyte. The elution of can be suppressed. Such coatings include _CeO2 , _SiO2 , _MgO , _Al2O3 , ZrO2, _{TiO2 ,} ZnO, _RuO2 , _{SnO2 ,} CoO, _Nb2O5 , CuO _{, V2O5} , _MoO3 , One or more selected from La ₂ O ₃ , WO ₃ , AlF ₃ , NiF ₂ , MgF ₂ , Li ₃ PO ₄ , Li ₄ P ₂ O ₇ , LiPO ₃ , Li ₂ PO ₃ F, and LiPO ₂ F ₂ Two or more types or a composite thereof can be used.

The average particle size as primary particles of the NCA-based composite oxide represented by the above formula (2), the average particle size of the composite oxide secondary particles (A) formed by agglomeration of the above primary particles, and The internal porosity of the secondary particles is the same as that of the NCM-based composite oxide particles (A) described above. That is, the average particle diameter of the NCA-based composite oxide particles represented by the above formula (2) as primary particles is preferably 500 nm or less, more preferably 300 nm or less, and the NCA-based composite oxide particles consisting of the above primary particles The average particle size of the oxide secondary particles (A) is preferably 25 μm or less, more preferably 20 μm or less. Further, the internal porosity of the NCA-based composite oxide secondary particles (A) made of the NCA-based composite oxide particles represented by the above formula (2) is 4% by volume to 4% by volume based on 100% of the volume of such secondary particles. 12% by volume is preferred, and 5% to 10% by volume is more preferred.
By having such an average particle size and internal porosity, on the surface of the NCA-based composite oxide secondary particles (A) consisting of the NCA-based composite oxide particles represented by the above formula (2), the NCA-based composite oxide The particles and the lithium positive electrode active material particles (B) are composited, and the lithium positive electrode active material particles (B) are supported so as to cover the surface of the secondary particles, so that the NCA-based composite oxide The discharge capacity and rate characteristics of the resulting lithium ion secondary battery can be sufficiently increased while effectively suppressing the elution of metal components (Ni, Co, Al, M ² ) contained in the particles.

The lithium composite oxide secondary particles (A) of the present invention are a mixture of NCM-based composite oxide particles represented by the above formula (1) and NCA-based composite oxide particles represented by the above formula (2). You can. The mixed state is a secondary particle formed by the coexistence of primary particles that are NCM-based composite oxide particles represented by the above formula (1) and primary particles that are NCA-based composite oxide particles represented by the above formula (2). Secondary particles may be formed, and secondary particles may be formed only of NCM-based composite oxide particles represented by the above formula (1) and NCA-based composite oxide particles represented by the above formula (2). Secondary particles may be mixed, and further, primary particles that are NCM-based composite oxide particles represented by the above formula (1) and NCA-based composite oxide particles represented by the above formula (2) may be mixed. Secondary particles formed by the coexistence of primary particles, secondary particles consisting only of NCM-based composite oxide particles expressed by the above formula (1), and only NCA-based complex oxide particles expressed by the above formula (2) The secondary particles may also be mixed.

NCM-based composite oxide particles and NCA-based composite oxide particles when NCM-based composite oxide particles represented by the above formula (1) and NCA-based composite oxide particles represented by the above formula (2) coexist. The ratio (mass %) may be adjusted as appropriate depending on the desired battery characteristics. For example, when placing importance on rate characteristics, it is preferable to increase the proportion of NCM-based composite oxide particles represented by the above formula (1). Specifically, NCM-based composite oxide particles and NCA-based The mass ratio of the composite oxide particles (NCM-based composite oxide:NCA-based composite oxide) is preferably 99.9:0.1 to 60:40. For example, when placing emphasis on battery capacity, it is preferable to increase the proportion of NCA-based composite oxide particles represented by the above formula (2). Specifically, for example, NCM-based composite oxide particles The mass ratio of NCM-based composite oxide and NCA-based composite oxide particles (NCM-based composite oxide:NCA-based composite oxide) is preferably 40:60 to 0.1:99.9.

The lithium positive electrode active material particles (B) constituting the positive electrode active material composite (D) for lithium ion secondary batteries of the present invention can be expressed by the following formula (3), formula (4), formula (5), or formula (6). ):
^LiM3gCohO2 ... _{( 3 )}
(In formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) In, g and h indicate numbers that satisfy 0≦g≦0.1, 0<h≦1, and (valence of M ³ )×g+3h=3.)
LiM ⁴ _i Mn _j O ₄ ...(4)
(In formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In formula (4), i and j represent numbers satisfying 0≦i≦0.1, 0<j≦2, and (valence of ^M4 )×i+(valence of Mn)×j=7 .)
LiNik _{Mn 1-k} O ₄ ...(5)
(In formula (5), k represents a number satisfying 0.3≦k≦0.7.)
_Li2MnO3 ^-LiM6O2 _... ( ₆ )
(In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. (Indicates one or more elements selected from.)
The lithium positive electrode active material particles (B) are supported in a composite manner with the lithium composite oxide particles so as to cover the surface of the lithium composite oxide secondary particles (A).

Above formula (3):
^LiM3gCohO2 _{... (} 3 ₎
(In formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) In, g and h indicate numbers that satisfy 0≦g≦0.1, 0<h≦1, and (valence of M ³ )×g+3h=3.)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material having a layered rock salt crystal structure.

In the lithium positive electrode active material particles (B) represented by the above formula (3), from the viewpoint of developing good cycle characteristics, M ³ is one or more elements selected from Ni and Mn. More preferably, 50 mol% or more of M ³ is Ni.
Specifically, LiCoO ₂ , LiMn _0.05 Co _0.95 O ₂ , LiAl _0.05 Co _0.95 O ₂ , LiMg _0.03 Co _0.98 O ₂ , and LiSi _0.03 Co _0.96 O ₂ can be used. Among them, LiCoO ₂ is preferred.

The average particle diameter of the lithium positive electrode active material particles (B) represented by the above formula (3) is determined from the viewpoint that the lithium positive electrode active material particles (B) are densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, the wavelength is preferably 100 nm to 500 nm, more preferably 100 nm to 400 nm, and even more preferably 100 nm to 300 nm.

The amount of the lithium positive electrode active material particles (B) represented by the above formula (3) supported by the lithium composite oxide secondary particles (A) is as follows: ) from the viewpoint of maximizing the performance as an active material, preferably 5% by mass to 50% by mass in 100% by mass of the total amount of positive electrode active material composite (D) for lithium ion secondary batteries obtained by composite. % by mass, more preferably 7% by mass to 45% by mass, still more preferably 9% by mass to 40% by mass.

At this time, a support layer of lithium positive electrode active material particles (B) is formed on the surface of the lithium composite oxide secondary particles (A) by supporting the lithium positive electrode active material particles (B) represented by formula (3). The thickness is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, even more preferably 500 nm to 3 μm.

The above formula (4):
LiM ⁴ _i Mn _j O ₄ ...(4)
(In formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In formula (4), i and j represent numbers satisfying 0≦i≦0.1, 0<j≦2, and (valence of ^M4 )×i+(valence of Mn)×j=7 .)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material having a layered rock salt crystal structure.

Specifically, the lithium positive electrode active material particles (B) represented by the above formula (4) include LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiCoMnO ₄ , LiCrMnO ₄ , LiFeMnO ₄ , LiAlMnO ₄ , LiCu _0.5 Mn _1.5 O ₄ can be used. Among them, LiMn ₂ O ₄ is preferred.

The average particle diameter of the lithium positive electrode active material particles (B) expressed by the above formula (4) is determined from the viewpoint that the lithium positive electrode active material particles (B) are densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, the wavelength is preferably 100 nm to 500 nm, more preferably 100 nm to 400 nm, and even more preferably 100 nm to 300 nm.

Amount of supported lithium positive electrode active material particles (B) represented by formula (4) in positive electrode active material composite (D) for lithium ion secondary batteries and support of lithium positive electrode active material particles (B) formed by the support The thickness of the layer is the same as that of the lithium positive electrode active material particles (B) represented by the above formula (3), and the supported amount is 100% of the total amount of the positive electrode active material composite for lithium ion secondary batteries (D). In the mass %, preferably 5 mass % to 50 mass %, more preferably 7 mass % to 45 mass %, still more preferably 9 mass % to 40 mass %, and the thickness of the support layer is Preferably it is 100 nm to 3 μm, more preferably 300 nm to 3 μm, even more preferably 500 nm to 3 μm.

The above formula (5):
LiNik _{Mn 1-k} O ₄ ...(5)
(In formula (5), k represents a number satisfying 0.3≦k≦0.7.)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material having a spinel structure.

Specifically, as the lithium positive electrode active material particles (B) represented by the above formula (5), LiNi _0.4 Mn _0.6 O ₄ , LiNi _0.5 Mn _0.5 O ₄ , and LiNi _0.6 Mn _0.4 O ₄ can be used. . Among them, LiNi _0.5 Mn _0.5 O ₄ is preferred.

The average particle size of the lithium positive electrode active material particles (B) represented by the above formula (5) is determined from the viewpoint that the lithium positive electrode active material particles (B) are densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, the wavelength is preferably 100 nm to 500 nm, more preferably 100 nm to 400 nm, and even more preferably 100 nm to 300 nm.

Amount of supported lithium positive electrode active material particles (B) represented by formula (5) in positive electrode active material composite (D) for lithium ion secondary batteries and support of lithium positive electrode active material particles (B) formed by the support The thickness of the layer is the same as that of the lithium positive electrode active material particles (B) represented by the above formulas (3) and (4), and the supported amount is the same as that of the positive electrode active material composite for lithium ion secondary batteries ( It is preferably 5% by mass to 50% by mass, more preferably 7% by mass to 45% by mass, even more preferably 9% by mass to 40% by mass, in 100% by mass of the total amount of D). The thickness is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, even more preferably 500 nm to 3 μm.

Above formula (6):
_Li2MnO3 ^-LiM6O2 _... ( ₆ )
(In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. (Indicates one or more elements selected from.)
The lithium positive electrode active material particles (B) represented by are particles made of a lithium positive electrode active material that forms a solid solution having a layered rock salt crystal structure.

From the viewpoint of developing good cycle characteristics, the lithium positive electrode active material particles (B) represented by the above formula (6) include one or more types selected from Co, Ni, and Mn as ^M6 . Preferably, it is an element.
Specifically, Li ₂ MnO ₃ -LiNiO ₂ , Li ₂ MnO ₃ -LiCoO ₂ , Li ₂ MnO ₃ -LiMn ₂ O ₄ , Li ₂ MnO ₃ -LiNi _x Mn _1-x O ₂ (0<x<1 ), Li ₂ MnO ₃ -LiNi _x Co _1-x O ₂ (0<x<1), Li ₂ MnO ₃ -LiCo _x Mn _1-x O ₂ (0<x<1), Li ₂ MnO ₃ -LiNi _1-x-y Co _x Mn _y O ₂ (0<x<1, 0<y<1, 0<x+y<1) can be used. Among them, Li ₂ MnO ₃ --LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is preferred.

The average particle size of the lithium positive electrode active material particles (B) expressed by the above formula (6) is determined from the viewpoint that the lithium positive electrode active material particles (B) are densely composited with the lithium composite oxide particles only on the surface of the lithium composite oxide secondary particles (A). Therefore, the wavelength is preferably 50 nm to 200 nm, more preferably 50 nm to 150 nm, and even more preferably 50 nm to 100 nm.

The supported amount of lithium positive electrode active material particles (B) represented by formula (6) in the positive electrode active material composite for lithium ion secondary batteries (D) is as follows: It is preferably 5% to 50% by mass, more preferably 7% to 45% by mass, even more preferably 9% to 40% by mass, based on the total amount of 100% by mass, and the thickness of the supporting layer The thickness is preferably 100 nm to 3 μm, more preferably 300 nm to 3 μm, even more preferably 500 nm to 3 μm.

The lithium positive electrode active material particles (B) represented by the above formula (3), formula (4), formula (5), or formula (6) have a lithium-based solid electrolyte (C) supported on the surface thereof. .
Content of lithium composite oxide secondary particles (A) in positive electrode active material composite for lithium ion secondary battery (D) and total content of lithium positive electrode active material particles (B) and lithium-based solid electrolyte (C) The mass ratio ((A):(B)+(C)) is preferably 95:5 to 50:50, more preferably 93:7 to 55:45, even more preferably 91:9. ~57:43.

The thickness of the supporting layer of the lithium-based solid electrolyte (C) that covers the entire surface of the lithium positive electrode active material particles (B) is preferably 1 nm to 20 nm, more preferably 5 nm to 20 nm. , more preferably 10 nm to 20 nm.
Here, the thickness of the supporting layer of the lithium-based solid electrolyte refers to the thickness of the lithium-based solid electrolyte support layer, which is determined by TEM observation of the cross section of the lithium positive electrode active material particles (B) having the lithium-based solid electrolyte (C) supported on the surface. It means the average value of the measured thickness of the supporting layer of the lithium-based solid electrolyte (C) on the surface of the lithium positive electrode active material particles (B), and has the same meaning in the following description.

The lithium-based solid electrolyte (C) supported on the surface of the lithium positive electrode active material particles (B) has at least good lithium ion conductivity, and can be formed in the firing step in the manufacturing method described below. It is a lithium-based solid electrolyte that can Specifically, for example, one or more of Li ₃ PO ₄ -Li ₄ SiO ₄ and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ can be mentioned, and among them, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is preferred.

The average particle size of the lithium-based solid electrolyte (C) is preferably 1 nm to 10 nm, more preferably 1 nm to 8 nm, and even more preferably 1 nm to 5 nm.
Here, the average particle size of the lithium-based solid electrolyte (C) is determined by the diffraction contrast on the surface of the lithium positive electrode active material particles (B) in TEM observation of the cross section of the lithium positive electrode active material particles (B). It means the average value of the measured values of the particle diameter (long axis length) of several dozen lithium-based solid electrolyte particles, and the same meaning will apply in the following description.

The average particle size of the positive electrode active material composite (D) for lithium ion secondary batteries of the present invention is preferably 2 μm to 30 μm, more preferably 3 μm to 20 μm, particularly preferably 5 μm to 15 μm. When the average particle size of the positive electrode active material composite (D) for lithium ion secondary batteries is smaller than 2 μm, the tap density decreases and sufficient peel strength cannot be imparted to the prepared electrode, resulting in poor cycle characteristics of the battery. There is a risk that it will decrease. Moreover, if the average particle size is larger than 30 μm, it becomes difficult to uniformly apply the electrode, and a uniform electrode may not be obtained, which may reduce the discharge capacity of the battery.
Further, the tap density of the positive electrode active material composite (D) for lithium ion secondary batteries of the present invention is preferably 0.5 g/cm ³ to 3.5 g/cm ³ , more preferably 1.5 g/cm 3 ³ to 3.5 g/cm ³ . If the tap density of the positive electrode active material composite (D) for a lithium ion secondary battery is smaller than 0.5 g/cm ³ , the cycle characteristics of the battery may deteriorate as described above.

The positive electrode active material composite (D) for a lithium ion secondary battery of the present invention is produced by the following steps (I) to (III):
(I) After preparing a slurry (a-1) containing the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C) and having a solid content concentration of 20% to 65% by mass, hot air The ratio (G/S) of supply amount G (L/min) of slurry (a-1) to supply amount S (L/min) of slurry (a-1) is 500 to 10,000 to obtain granules (a). The process of obtaining
(II) The obtained granules (a) are fired at 500°C to 800°C for 10 minutes to 3 hours, and the lithium positive electrode active material particles (B ), and (III) obtaining a pre-granulated product (b) with a porosity of 45% to 80% by volume, and (III) obtaining a pre-granulated product (b) and lithium composite oxide secondary particles (A ) while applying compressive force and shearing force to crush the pre-granulated material (b), and produce lithium positive electrode active material particles (B) having a lithium-based solid electrolyte (C) supported on the surface. ) and lithium composite oxide secondary particles (A). In this way, by going through the step (II) of obtaining the pre-granulated material (b) with high porosity consisting of lithium positive electrode active material particles (B), the subsequent step (III) can be easily carried out without applying an excessive load. The pre-granulated material (b) can be crushed and made into fine particles. In this way, the preliminary granules (b) consisting of the lithium positive electrode active material particles (B) with the lithium-based solid electrolyte (C) supported on the surface are finely granulated, while the lithium positive electrode active material particles ( B) is separated and supplied, and the lithium positive electrode active material particles (B) related to the lithium composite oxide particles are supported on the surface of the lithium composite oxide secondary particles (A) while being efficiently and well composited. It becomes possible to do so.

Step (I) included in the production method of the present invention includes preparing a slurry (a-1) containing lithium positive electrode active material particles (B) and a raw material compound of a lithium-based solid electrolyte (C), and then A step of obtaining granules (a) by spray drying under conditions where the ratio (G/S) between G (L/min) and the supply amount S (L/min) of slurry (a-1) is 500 to 10,000. It is.

The lithium positive electrode active material particles (B) used in step (I) have a lithium-based solid electrolyte (C) supported on their surfaces in the next step (II), and then are lithium composite oxide secondary particles in the subsequent step (III). These are particles of lithium positive electrode active material represented by the above formulas (3) to (6) that are composited on the surface of (A), and the average particle diameter is represented by the above formulas (3) to (5). The diameter is 100 nm to 500 nm when using lithium positive electrode active material particles (B) represented by formula (6), and 50 nm to 200 nm when using lithium positive electrode active material particles (B) represented by formula (6).

The content of the lithium positive electrode active material particles (B) in the slurry (a-1) is preferably 30 parts by mass to 185 parts by mass, more preferably 50 parts by mass to 150 parts by mass, based on 100 parts by mass of water. It is.

The raw material compound of the lithium-based solid electrolyte (C) constituting the granules (a) is fired in the next step (III) to produce the lithium-based solid electrolyte (C). The raw material compounds to be used are preferably those that dissolve in the slurry (a-1), and each element constituting the lithium-based solid electrolyte (C), specifically titanium, lithium, aluminum, silicon, boron, and water of phosphorus. Examples include, but are not limited to, oxides, carbonates, sulfates, acetates, and the like.

In order to support the lithium-based solid electrolyte (C) produced from the raw material compound by firing in the next step (III) on the surface of the lithium positive electrode active material particles (B), the lithium in the slurry (a-1) The total content of the raw material compounds of the system solid electrolyte (C) is the total amount of the lithium positive electrode active material particles (B) obtained in the next step (III) and the lithium-based solid electrolyte (C) supported on the particle surface. The amount is desirably 0.1% by mass to 15% by mass in 100% by mass. Specifically, for example, it is preferably 0.03 parts by mass to 35 parts by mass, more preferably 0.05 parts by mass to 20 parts by mass, per 100 parts by mass of water in slurry (a-1).
The solid content concentration in 100% by mass of slurry (a-1) is 20% by mass to 65% by mass, preferably 30% to 60% by mass, more preferably 40% to 55% by mass. %.

In preparing the slurry (a-1), a process is performed using a dispersion machine (homogenizer) in order to uniformly disperse the lithium positive electrode active material particles (B) and the dissolved lithium-based solid electrolyte (C) raw material. It is preferable. Examples of such a dispersing machine include a disintegrating machine, a beating machine, a low-pressure homogenizer, a high-pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short-screw extruder, a twin-screw extruder, an ultrasonic stirrer, a household juicer mixer, etc. Can be mentioned. Among these, an ultrasonic stirrer is preferred from the viewpoint of dispersion efficiency. The degree of dispersion uniformity of slurry (a-1) can be quantitatively evaluated, for example, by the light transmittance using a UV/visible light spectrometer or the viscosity using an E-type viscometer, or by visual observation. It can also be easily evaluated by confirming that the white turbidity is uniform. The time for treatment with a disperser is preferably 1 minute to 30 minutes, more preferably 2 minutes to 15 minutes.

Next, the obtained slurry (a-1) is heated at a ratio (G/S) of supply amount G (L/min) of hot air to supply amount S (L/min) of slurry (a-1) of 500 to Spray drying is carried out under the conditions of 10,000 to obtain granules (a). The granules (a) undergo the next step (II) to obtain preliminary granules (formed from lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported). b). In the production method of the present invention, it is possible to avoid using strong secondary particles formed by firmly aggregating lithium positive electrode active material particles (B), and to easily crush them without applying an excessive load. Since the preliminary granules (b) are used, the lithium positive electrode active material particles (B) constituting the preliminary granules (b) can be processed into lithium composite oxide without requiring excessive shearing force or the like. This enables it to be supported on the surface of the secondary particles (A).

The ratio (G/S) between the supply amount G (L/min) of the hot air and the supply amount S (L/min) of the slurry (a-1) is 500 to 10000, preferably 1000 to 9000. . The hot air temperature during spray drying is preferably 110°C to 160°C, more preferably 120°C to 140°C.

The particle size of the granulated product (a) obtained in step (I) is preferably 5 μm to 25 μm, more preferably 5 μm to 15 μm, as measured by the D ₅₀ value in the particle size distribution based on laser diffraction/scattering method.
Here, the D ₅₀ value in particle size distribution measurement is a value obtained by volume-based particle size distribution based on laser diffraction/scattering method, and the D ₅₀ value means the particle size at 50% cumulative (median diameter). .

Step (II) included in the production method of the present invention is to sinter the granules (a) obtained in step (I) at 500°C to 800°C for 10 minutes to 3 hours so that the porosity becomes 45% by volume. This is the step of obtaining a pre-granulated material (b) of ~80% by volume. By going through this step (II), the lithium-based solid electrolyte (C) is firmly supported on the surface of the lithium positive electrode active material particles (B) constituting the preliminary granules (b), and the porosity is increased to 45% by volume. It is possible to form a pre-granulated material (b) having an appropriate crushability adjusted to % to 80% by volume.

The firing temperature is determined from the viewpoint of effectively generating the lithium-based solid electrolyte (C), and from the viewpoint of imparting appropriate crushability by adjusting the porosity of the preliminary granules (b) to 45% to 80% by volume. 500°C to 800°C, preferably 600°C to 770°C, more preferably 650°C to 750°C. Further, the firing time is 10 minutes to 3 hours, preferably 30 minutes to 1.5 hours.

The porosity of the preliminary granules (b) consisting of lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is 45% by volume to 80% by volume based on the mercury intrusion method. %, preferably 50% to 80% by volume.

Further, the tap density of the preliminary granules (b) consisting of lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is preferably 3.5 g/cm ³ or less, and more preferably Preferably it is 1.5 g/cm ³ to 3.5 g/cm ³ .

Furthermore, the average particle size of the pre-granulated material (b) consisting of lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is D ₅₀ in the particle size distribution based on the laser diffraction/scattering method. The value is preferably 5 μm to 25 μm, more preferably 5 μm to 15 μm.

The crushing strength of the preliminary granules (b) consisting of lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported is preferably 1.8 KN/mm or less, more preferably It is 1.75KN/mm or less. The crushing strength refers to the ease with which the preliminary granules (b) made of lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported can be crushed by compression. It means the value determined by equation (7).
Crushing strength of pre-granulated material (b) (KN/mm) = 10/(t ₀ - t ₁₀ )...(7) t ₀ in formula (7) is 3 g of pre-granulated material (b) consisting of lithium positive electrode active material particles (B) on which a lithium-based solid electrolyte (C) is supported is added to the lithium-ion solid electrolyte (C), and after repeated tapping by dropping from a height of 1 cm 10 times, the densification is confirmed. Indicates the layer thickness (mm) of the pre-granulated material (b) in the packed state, and _t10 is the layer thickness (mm) of the pre-granulated material (b) in the densely packed state when a load of 10 KN is applied from above. The layer thickness (mm) of object (b) is shown.

Step (III) included in the production method of the present invention is to combine the preliminary granules (b) obtained in step (II) with the lithium composite oxide secondary particles (A) while applying compressive force and shear force. While mixing and crushing the preliminary granules (b), lithium positive electrode active material particles (B) having a lithium-based solid electrolyte (C) supported on their surfaces and lithium composite oxide secondary particles (A) are mixed. This is the process of combining the Through this process, the preliminary granules (b) were crushed on the surface of the lithium composite oxide secondary particles (A), and the lithium-based solid electrolyte (C) was supported on the surface. It is possible to obtain a positive electrode active material composite for a lithium ion secondary battery (D) in which fine lithium positive electrode active material particles (B) are supported so as to be densely and extensively covered.

In step (III), the mixture of the lithium composite oxide secondary particles (A) and the preliminary granules (b) is sufficiently dry mixed before being mixed while applying compressive force and shear force. preferable. As for the dry mixing method, it is preferable to use an ordinary dry mixer such as a ball mill or a V-blender, and mixing using a planetary ball mill that can rotate around its axis is more preferable.

The process of mixing while applying compressive force and shear force (hereinafter also referred to as "compounding") is preferably performed in a closed container equipped with an impeller, rotor tool, etc. Examples of devices equipped with such a closed container include high-speed shear mills, blade-type kneaders, and high-speed mixers. Mechanofusion, a particle compounding device (manufactured by Coke Kogyo Co., Ltd.), Nobilta (manufactured by Hosokawa Micron Co., Ltd.), a surface modification device Miraro, a hybridization system (manufactured by Nara Kikai Seisakusho Co., Ltd.), and an Eirich intensive mixer (manufactured by Nippon Eirich Co., Ltd.) are preferably used. be able to. The temperature is preferably 5°C to 80°C, more preferably 10°C to 50°C. Further, the atmosphere is not particularly limited, but is preferably an inert gas atmosphere or an air atmosphere.

More specifically, for example, when Nobilta (manufactured by Hosokawa Micron Corporation), which is a dry particle compositing device equipped with an impeller, is used as a device for compositing, the rotation speed of the impeller is set to ), the surface of the lithium composite oxide secondary particles (A) is well coated with the lithium positive electrode active material particles (B) on which the lithium-based solid electrolyte (C) is supported. From the viewpoint of obtaining a supported composite oxide, the speed is preferably 2000 rpm to 6000 rpm, more preferably 2000 rpm to 4000 rpm. Further, the time for compounding is preferably 1 minute to 10 minutes, more preferably 1 minute to 7 minutes.
Further, when an Eirich intensive mixer (manufactured by Nippon Eirich Co., Ltd.), which is a high-speed stirring mixer equipped with a rotor tool, is used as a device for performing such compounding, the rotation speed of the rotor tool is preferably 2000 rpm to 8000 rpm. The speed is more preferably 2000 rpm to 6000 rpm. Further, the time for compounding is preferably 1 minute to 10 minutes, more preferably 1 minute to 7 minutes.

In step (III), the time for the above-mentioned compounding and/or the rotation speed of the impeller etc. depend on the amount of the mixture of lithium composite oxide secondary particles (A) and preliminary granules (b) to be charged into the closed container. It is necessary to adjust accordingly. Then, by operating the sealed container, compressive force and shear force are applied to the mixture between the impeller, etc. and the inner wall of the sealed container, and while the preliminary granules (b) are finely crushed, the lithium composite It is now possible to perform a process of compositing oxide secondary particles (A) and lithium positive electrode active material particles (B) on which a lithium-based solid electrolyte (C) is supported. Lithium ion secondary particles (C) supported on the lithium positive electrode active material particles (B) are supported on the surfaces of the lithium composite oxide secondary particles (A) so as to be well composited and coated. A battery positive electrode active material composite (D) can be obtained.
For example, when the above-mentioned compounding is performed for 1 minute to 8 minutes in a closed container equipped with an impeller that rotates at a rotation speed of 2000 rpm to 5000 rpm, the amount of the above mixture to be put into the closed container is the effective container (closed container equipped with an impeller). Among them, the amount is preferably 0.1 g to 0.7 g, more preferably 0.15 g to 0.4 g per 1 cm ³ of the container (corresponding to the area that can accommodate the above mixture).

The mass of the compounding amount of the lithium composite oxide secondary particles (A) to be composited in step (III) and the compounding amount of the lithium positive electrode active material particles (B) having the lithium-based solid electrolyte (C) supported on the surface The ratio (particles (A): particles (B) + particles (C)) is the content of lithium composite oxide secondary particles (A) in the positive electrode active material composite for lithium ion secondary batteries (D) and the lithium The mass ratio ((A):(B)+(C)) of the total content of the positive electrode active material particles (B) and the lithium-based solid electrolyte (C) is the same as that of the above mixture. What is necessary is just to adjust the amount of pre-granulated material (b) in .

In particular, if the positive electrode active material composite for lithium ion secondary batteries of the present invention is applied as a positive electrode material, and the lithium ion secondary batteries containing the same include a positive electrode, a negative electrode, an electrolyte, and a separator as essential components, Not limited.

Here, the material composition of the negative electrode is not particularly limited as long as it can occlude lithium ions during charging and release them during discharging, and any known material composition can be used. For example, lithium metal, graphite, silicon-based (Si, SiO _x ), lithium titanate, carbon materials such as amorphous carbon, etc. can be used. It is preferable to use an electrode made of an intercalating material that can electrochemically absorb and release lithium ions, particularly a carbon material. Furthermore, two or more of the above negative electrode materials may be used in combination; for example, a combination of graphite and silicon may be used.

The electrolytic solution is one in which a supporting salt is dissolved in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is generally used in electrolytes of lithium ion secondary batteries, and examples thereof include carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, Lactones, oxolane compounds, etc. can be used.

The supporting salt is not particularly limited in type, but includes inorganic salts selected from LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , derivatives of the inorganic salts, LiSO ₃ CF ₃ , LiC(SO ₃ CF ₃ ) ₂ and an organic salt selected from LiN(SO ₃ CF ₃ ) ₂ , LiN(SO ₂ C ₂ F ₅ ) ₂ and LiN(SO ₂ CF ₃ )(SO ₂ C ₄ F ₉ ), and a derivative of the organic salt. It is preferable that it is at least one kind of.

The separator serves to electrically insulate the positive electrode and the negative electrode and to retain the electrolyte. For example, a porous synthetic resin membrane, particularly a porous membrane of polyolefin polymer (polyethylene, polypropylene) may be used.

The shape of the lithium ion secondary battery having the above structure is not particularly limited, and may be various shapes such as a coin shape, a cylindrical shape, a square shape, or an irregular shape enclosed in a laminate exterior body. .

Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not limited to these Examples.

[Production Example 1: Production of lithium composite oxide secondary particles (A-1)]
After mixing 263 g of nickel sulfate hexahydrate, 281 g of cobalt sulfate heptahydrate, 241 g of manganese sulfate pentahydrate, and 3 L of water so that the molar ratio of Ni:Co:Mn was 1:1:1. 25% ammonia water was added dropwise to the mixed solution at a dropping rate of 300 ml/min to obtain slurry A1 containing the metal composite hydroxide having a pH of 11.
Next, the slurry A1 was filtered and dried to obtain a metal composite hydroxide mixture A2, and then 37 g of lithium carbonate was mixed with the mixture A2 using a ball mill to obtain a powder mixture A3.
The obtained powder mixture A3 was pre-calcined in the air at 800°C for 5 hours, pulverized, and then granulated.Then, the powder mixture A3 was calcined in the air at 800°C for 10 hours to form a lithium composite oxide. Secondary particles (A-1) (LiNi _0.33 Co _0.33 Mn _0.34 O ₂ , average particle size 10 μm) were obtained.

[Production Example 2: Production of lithium composite oxide secondary particles (A-2)]
Mix 370 g of lithium carbonate, 950 g of nickel carbonate, 150 g of cobalt carbonate, 58 g of aluminum carbonate, and 3 L of water so that the molar ratio of Li:Ni:Co:Al is 1:0.8:0.15:0.05. After that, the mixture was mixed in a ball mill to obtain a powder mixture A4. The obtained powder mixture A4 was pre-calcined in an air atmosphere at 800°C for 5 hours and crushed, and then main calcination was performed in an air atmosphere at 800°C for 24 hours to form lithium composite oxide secondary particles (A -2) (LiNi _0.8 Co _0.15 Al _0.05 O ₂ , average particle size 10 μm) was obtained.

[Production Example 3: Production of particles (BC-1) in which lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
Powders of 222 g of lithium carbonate and 482 g of cobalt oxide were mixed in a ball mill so that the molar ratio of Li:Co was 1:1 to prepare a powder mixture B1. Powder mixture B1 was compacted at a molding pressure of 500 kg/cm ³ and pre-calcined at 700° C. for 5 hours in an air atmosphere. Thereafter, this molded body was crushed and mixed again, compacted at a molding pressure of 1000 kg/cm ³ , and fired at 900° C. for 10 hours in an air atmosphere to obtain lithium cobalt oxide (LiCoO ₂ ). The obtained lithium cobalt oxide was pulverized to obtain a particle size suitable for composite formation to obtain lithium cobalt oxide particles B2 (LiCoO ₂ , average particle size 200 nm).
500g of the obtained lithium cobalt oxide particles B2 were collected and mixed with 1.8g _{of LiNO3} , _2.25g of Al( _NO3 ) _3.9H2O , 6.46g _{of TiCl4} , and _5.88g of 85% _H3PO4 . , 500 mL of water was added, and further 21.86 g of 28% ammonia water was added as a pH adjuster to obtain slurry B3 (solid content concentration 51%). The obtained slurry B3 was dispersed for 1 minute using an ultrasonic stirrer (T25, manufactured by IKA) to uniformly color the entire slurry, and then dispersed using a spray drying device (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.). The pre-granulated product B4 was obtained by spray drying.
The obtained preliminary granules B4 _were fired at 700°C for 1 _hour in an air atmosphere to _{form particles} ( _BC- 1) (LiCoO ₂ , average particle size: 200 nm, thickness of lithium-based solid electrolyte support layer: 5 nm) was obtained.

[Production Example 4: Production of particles (BC-2) in which lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
In Production Example 3, 500 g of the obtained lithium cobalt oxide particles B2 were collected, and 18 g of LiNO ₃ , 22.5 g of Al(NO ₃ ) ₃ .9H ₂ O, 64.6 g of TiCl ₄ , 58% of 85% H ₃ PO ₄ Lithium was prepared in the same manner as in Production Example 3, except that slurry B5 (solid content concentration 42%) was obtained by adding 218.6 g of 28% ammonia water as a pH adjuster. Particles (BC-2) in which Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of positive electrode active material particles (LiCoO ₂ , average particle size: 200 nm, thickness of lithium-based solid electrolyte support layer: 20 nm) ) was obtained.

[Production Example 5: Production of particles (BC-3) in which lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
Lithium manganate (LiMn ₂ After obtaining O ₄ ), the obtained lithium manganate was pulverized to obtain lithium manganate particles B6 (LiMn ₂ O ₄ , average particle size 200 nm).
500 g of the obtained lithium manganate particles B6 were collected and mixed with 1.8 g of LiNO ₃ , 2.25 g of Al ₍ NO ₃ ) 3.9H ₂ O, 6.46 g of TiCl ₄ , and 5.88 g of 85% H ₃ PO ₄ , 500 mL of water was added, and further 21.86 g of 28% ammonia water was added as a pH adjuster to obtain slurry B7 (solid content concentration 51%). The obtained slurry B7 was dispersed for 1 minute using an ultrasonic stirrer (same as above) to uniformly color the entire slurry, and then spray-dried using a spray dryer (same as above) to obtain pre-granulated material B8. I got it.
_The obtained preliminary granules B8 _were fired at 700° C. for 1 _hour in an _air atmosphere to form _particles (BC- 3) (LiMn ₂ O ₄ , average particle size: 200 nm, thickness of lithium-based solid electrolyte support layer: 5 nm) was obtained.

[Production Example 6: Production of particles (BC-4) in which lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
After mixing 147.8 g of lithium carbonate, 149.4 g of nickel oxide, and 690 g of manganese carbonate in a ball mill so that the molar ratio of Li:Ni:Mn was 2:1:3, the mixture was heated at 900° C. After baking for a time to obtain LiNi _0.5 Mn _1.5 O ₄ , it was pulverized to obtain LiNi _0.5 Mn _1.5 O ₄ particles B9 (average particle size 200 nm).
500 g of the obtained LiNi _0.5 Mn _1.5 O ₄ particles B9 were collected, and 1.8 g of LiNO ₃ , 2.25 g of Al ₍ NO ₃ ) 3.9H ₂ O, 6.46 g of TiCl ₄ , 85% H ₃ PO ₄ 5 .88 g and 500 mL of water were added, and further 21.86 g of 28% ammonia water was added as a pH adjuster to obtain slurry B10 (solid content concentration 51%). The obtained slurry B10 was dispersed for 1 minute using an ultrasonic stirrer (same as above) to uniformly color the entire slurry, and then spray-dried using a spray dryer (same as above) to obtain pre-granulated material B11. I got it.
_The obtained preliminary granules B11 _were fired at ₇₀₀ ° C. _for 1 _hour in an air atmosphere to form particles (BC- 4) (LiNi _0.5 Mn _1.5 O ₄ , average particle size: 200 nm, thickness of lithium-based solid electrolyte support layer: 5 nm) was obtained.

[Production Example 7: Production of particles (BC-5) in which lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
Add 1324 g of manganese acetate tetrahydrate, 323.5 g of nickel acetate tetrahydrate, 323.8 g of cobalt acetate tetrahydrate, 848 g of sodium carbonate, and 3 L of water, and while stirring while maintaining the solution at 60 ° C. After mixing, 28% ammonia water was added as a pH adjuster at a dropping rate of 300 ml/min until the pH reached 7.5, thereby obtaining slurry B12. The obtained slurry B12 was washed with water and dried, mixed with 487.7 g of lithium carbonate, and pre-calcined at 500°C for 5 hours, crushed, mixed, and fired at 900°C for 20 hours. .5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles B13 (average particle size: 100 nm) were obtained.
500 g of the obtained 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles B13 were collected, and 1.8 g of LiNO ₃ , _2.25 g of Al(NO ₃ ) 3.9H ₂ O, and TiCl ₄ 6.46 g, 85% H ₃ PO ₄ 5.88 g, and 500 mL of water were added, and further 21.86 g of 28% ammonia water was added as a pH adjuster to obtain slurry B14 (solid content concentration 51%). . The obtained slurry B14 was dispersed for 1 minute using an ultrasonic stirrer (same as above) to uniformly color the entire slurry, and then spray-dried using a spray dryer (same as above) to obtain pre-granulated material B15. I got it.
_The obtained preliminary granules B15 _were fired at 700° C. _for 1 _hour in an air atmosphere to form particles ( _BC- 5) (0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ , average particle size: 100 nm, thickness of lithium-based solid electrolyte support layer: 3 nm) was obtained.

[Production Example 8: Production of particles (BC-6) in which lithium-based solid electrolyte (C) is supported on lithium positive electrode active material particles (B)]
Mix 500 g of lithium cobalt oxide particles B2 (LiCoO ₂ , average particle size 200 nm) obtained during the process of Production Example 3 with 500 mL of water, 6.22 g of lithium hydroxide monohydrate, and 4.42 g of tetraethoxysilane. As a result, slurry B16 was obtained. Next, the obtained slurry B16 was stirred at a stirring speed of 200 rpm for 10 minutes while maintaining the temperature at 25 ° C., and 2.44 g of 85% phosphoric acid was added dropwise to the slurry while stirring was continued. After that, the slurry was further stirred for 30 minutes at a stirring speed of 200 rpm to obtain slurry B17 (solid content concentration 50%). The obtained slurry B17 was dispersed for 1 minute using an ultrasonic stirrer (same as above) to uniformly color the entire slurry, and then spray-dried using a spray dryer (same as above) to obtain pre-granulated product B18. I got it.
_The obtained preliminary granules B18 were fired at 700°C for 4 _hours in the air to obtain particles (BC _- 6) ( _{LiCoO 2} , average particle size: 200 nm, thickness of lithium-based solid electrolyte support layer: 5 nm).

[Production Example 9: Production of solid electrolyte particles (S-1)]
71.8 g of lithium nitrate, 90 g of aluminum nitrate nonahydrate, 516.8 g of titanium chloride, 235.2 g of phosphoric acid, and 874.2 g of 28% ammonia water as a pH adjuster were added, and the mixture was heated at 200 rpm using a planetary ball mill. After pulverizing and mixing for 2 hours, the mixture was dried to obtain mixture B19. The obtained mixture B19 was formed into pellets, fired at 900°C for 12 hours in an air atmosphere, and then crushed in a mortar to form solid electrolyte particles (S-1) (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , average particle size: 500 nm) was obtained.

[Example 1: Production of positive electrode active material composite (D-1) for lithium ion secondary battery]
300 g of lithium composite oxide secondary particles (A-1) obtained in Production Example 1 and 200 g of particles (BC-1) obtained in Production Example 3 were subjected to Mechanofusion (manufactured by Hosokawa Micron Corporation, AMS-Lab). A composite treatment was carried out for 10 minutes at 2600 rpm (20 m/sec) using the NCM-based composite oxide secondary particles (A) so that the lithium cobalt oxide particles (B) were supported on the surface of the NCM composite oxide secondary particles (A), and the lithium cobalt oxide particles were formed. Positive electrode active material composite for lithium ion secondary batteries (D-1) in which lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of particles (B) (average particle size 14 μm, surface Lithium cobalt oxide particles (B) having _a thickness _of 2 _μm and a tap density of 2.8 _g /cm ₃ ⁾ were obtained.

[Example 2: Production of positive electrode active material composite (D-2) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A ) lithium cobalt oxide particles (B) are supported on the surface of the lithium cobalt oxide particles (B), and a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium cobalt oxide particles (B). Positive electrode active material composite for secondary batteries (D-2) (average particle size 14 μm, made of lithium cobalt oxide particles (B) carrying a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface) A supporting layer thickness of 2 μm and a tap density of 2.6 g/cm ³ were obtained.

[Example 3: Production of positive electrode active material composite (D-3) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A ) lithium manganate particles (B) are supported on the surface of the lithium manganate particles (B), and the lithium solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium manganate particles (B). Positive electrode active material composite for secondary batteries (D-3) (average particle size 14 μm, made of lithium manganate particles (B) having a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported on the surface. A supporting layer thickness of 2 μm and a tap density of 2.2 g/cm ³ were obtained.

[Example 4: Production of positive electrode active material composite (D-4) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A ) _{, and a lithium-based solid electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 is supported on the surface of the LiNi 0.5 Mn 1.5 O 4 particles ( B ) .} Lithium ion secondary battery positive electrode active material composite (D-4) (average particle size 14 μm, LiNi _0.5 supported on the surface of a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃₎ A supporting layer of Mn _1.5 O ₄ particles (B) had a thickness of 2 μm and a tap density of 2.1 g/cm ³ ).

[Example 5: Production of positive electrode active material composite for lithium ion secondary battery (D-5)]
NCM-based composite oxide secondary particles (A ) are supported on the surface of 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles (B), and a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 is supported on the surface of the particles (B). Positive electrode active material composite (D-5) for lithium ion secondary batteries supported by (PO ₄ ) ₃ (average particle size 13 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface) A supporting layer of supported 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles (B) had a thickness of 1.5 μm and a tap density of 1.9 g/cm ³ ).

[Example 6: Production of positive electrode active material composite (D-6) for lithium ion secondary battery]
NCM-based composite oxide secondary particles (A) were prepared in the same manner as in Example 1 except that 300 g of lithium composite oxide secondary particles (A-1) were changed to 450 g and 200 g of particles (BC-1) were changed to 50 g. A lithium ion diode formed by carrying lithium cobalt oxide particles (B) on the surface of the lithium cobalt oxide particles, and a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported on the surface of the lithium cobalt oxide particles (B). Positive electrode active material composite for next battery (D-6) (average particle size 12 μm, supporting lithium cobalt oxide particles (B) with a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported on the surface) A layer thickness of 1 μm and a tap density of 2.6 g/cm ³ ) were obtained.

[Example 7: Production of positive electrode active material composite for lithium ion secondary battery (D-7)]
Same as Example 1 except that 300 g of lithium composite oxide secondary particles (A-1) was changed to 450 g, and 200 g of particles (BC-1) were changed to 50 g of particles (BC-3) obtained in Production Example 5. Lithium manganate particles (B) are supported on the surface of NCM-based composite oxide secondary particles (A), and lithium-based solid electrolyte Li _1.3 Al _0.3 Ti is supported on the surface of the lithium manganate particles (B). Positive electrode active material composite for lithium ion secondary batteries (D-7) supported by _1.7 (PO ₄ ) ₃ (average particle size 12 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface) lithium manganate particles (B) having a thickness of 1 μm and a tap density of 2.5 g/cm ³ ) were obtained.

[Example 8: Production of positive electrode active material composite for lithium ion secondary battery (D-8)]
Same as Example 1 except that 300 g of lithium composite oxide secondary particles (A-1) was changed to 450 g, and 200 g of particles (BC-1) were changed to 50 g of particles (BC-4) obtained in Production Example 6. LiNi _0.5 Mn _1.5 O ₄ particles (B) are supported on the surface of NCM-based composite oxide secondary particles (A), and a lithium-based solid electrolyte Li _1.3 Al _0.3 is supported on the surface of the particles (B). Positive electrode active material composite for lithium ion secondary batteries (D-8) supported by Ti _1.7 (PO ₄ ) ₃ (average particle size 12 μm, lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) on the surface) LiNi _0.5 Mn _1.5 O ₄ particles (B) having _a thickness of 1 μm and a tap density of 2.6 g/cm ³ ) were obtained.

[Example 9: Production of positive electrode active material composite for lithium ion secondary battery (D-9)]
Same as Example 1 except that 300 g of lithium composite oxide secondary particles (A-1) was changed to 450 g, and 200 g of particles (BC-1) were changed to 50 g of particles (BC-5) obtained in Production Example 7. 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles (B) are supported on the surface of NCM-based composite oxide secondary particles (A), and such particles (B) A positive electrode active material composite for lithium ion secondary batteries (D-9) comprising a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported on the surface (average particle size 11.5 μm, lithium on the surface). Thickness of support layer of 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles (B) supporting system solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ : 750 nm, tap A density of 2.4 g/cm ³ ) was obtained.

[Example 10: Production of positive electrode active material composite for lithium ion secondary battery (D-10)]
The NCA system was prepared in the same manner as in Example 1, except that 300 g of lithium composite oxide secondary particles (A-1) was changed to 300 g of lithium composite oxide secondary particles (A-2) obtained in Production Example 2. Lithium cobalt oxide particles (B) are supported on the surface of the composite oxide secondary particles (A), and a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) is supported on the surface of the lithium cobalt oxide particles (B). Positive electrode active material composite for lithium ion secondary batteries (D-10) (average particle size 14 μm, supporting lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface ₎ A supporting layer of lithium cobalt oxide particles (B) had a thickness of 2 μm and a tap density of 2.8 g/cm ³ ).

[Example 11: Production of positive electrode active material composite for lithium ion secondary battery (D-11)]
On the surface of NCM-based composite oxide secondary particles (A) in the same manner as in Example 1, except that 200 g of particles (BC-1) was changed to 200 g of particles (BC-6) obtained in Production Example 8. A positive electrode active material for a lithium ion secondary battery, in which lithium cobalt oxide particles (B) are supported, and a lithium-based solid electrolyte Li _3.5 Si _0.5 P _0.5 O ₄ is supported on the surface of the lithium cobalt oxide particles (B). Composite (D-11) (average particle size 14 μm, thickness of support layer of lithium cobalt oxide particles (B) with lithium-based solid electrolyte Li _3.5 Si _0.5 P _0.5 O ₄ supported on the surface: 2 μm, tap density 2.8 g/cm ³ ) was obtained.

[Comparative Example 1: Production of lithium composite particles (E-1)]
To 500 g of lithium composite oxide secondary particles (A-1) obtained in Production Example 1, 0.9 g of lithium nitrate, 1.13 g of aluminum nitrate nonahydrate, 3.23 g of titanium chloride, and 2.94 g of phosphoric acid were added. 500 mL of water was added, and 10.93 g of 28% ammonia water was further added as a pH adjuster to obtain slurry C1. The obtained slurry C1 was dispersed for 1 minute using an ultrasonic stirrer (T25, manufactured by IKA) to uniformly color the entire slurry, and then dispersed using a spray drying device (MDL-050M, manufactured by Fujisaki Electric Co., Ltd.). The pre-granulated product C2 was obtained by spray drying.
The obtained preliminary granules C2 are fired at 700° C. for 1 hour in an air atmosphere to form a lithium-based solid electrolyte Li _1.3 Al on the surface of lithium composite oxide secondary particles (LiNi _0.33 Co _0.33 Mn _0.34 O ₂ ). Lithium composite particles (E-1) supported by _0.3 Ti _1.7 (PO ₄ ) ₃ (average particle size: 10 μm, thickness of supporting layer of solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ : 5 nm, A tap density of 2.6 g/cm ³ ) was obtained.

[Comparative Example 2: Production of positive electrode active material composite (E-2) for lithium ion secondary battery]
300 g of lithium composite oxide secondary particles (A-1) obtained in Production Example 1 and 200 g of solid electrolyte particles (S-1) obtained in Production Example 9 were heated at 2600 rpm using Mechanofusion (same as above). (20 m/sec) for 10 minutes, and lithium-based solid electrolyte particles Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ are supported on the surface of NCM-based composite oxide secondary particles (A). A positive electrode active material composite (E-2) for lithium ion secondary batteries (average particle size 12 μm, thickness of lithium-based solid electrolyte particle support layer: 1 μm, tap density 2.0 g/cm ³ ) was obtained.

[Comparative Example 3: Production of positive electrode active material composite (E-3) for lithium ion secondary battery]
NCM-based composite oxide secondary particles were prepared in the same manner as in Example 1, except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of lithium cobalt oxide particles B2, which is an intermediate product of Production Example 3. Positive electrode active material composite (E-3) for lithium ion secondary batteries, in which lithium cobalt oxide particles are supported on the surface of (A) (average particle size 14 μm, thickness of supporting layer of lithium cobalt oxide particles: 2 μm, A tap density of 2.8 g/cm ³ ) was obtained.

[Comparative Example 4: Production of positive electrode active material composite (E-4) for lithium ion secondary battery]
NCM-based composite oxide secondary particles were prepared in the same manner as in Example 1, except that 200 g of lithium positive electrode active material particles (B-1) were changed to 200 g of lithium manganate particles B5, which is an intermediate product of Production Example 5. Positive electrode active material composite (E-4) for lithium ion secondary batteries, in which lithium manganate particles are supported on the surface of (A) (average particle size 14 μm, thickness of supporting layer of lithium manganate particles: 2 μm, A tap density of 2.2 g/cm ³ ) was obtained.

[Comparative Example 5: Production of positive electrode active material composite (E-5) for lithium ion secondary battery]
NCM-based composite oxide was prepared in the same manner as in Example 1, except that 200 g of lithium positive electrode active material particles (B-1) was replaced with 200 g of LiNi _0.5 Mn _1.5 O ₄ particles B8, which was an intermediate product of Production Example 6. Positive electrode active material composite for lithium ion secondary batteries (E-5) in which LiNi _0.5 Mn _1.5 O ₄ particles are supported on the surface of secondary particles (A) (average particle size 14 μm, LiNi _0.5 Mn _1.5 O ₄ particles) A supporting layer thickness of 2 μm and a tap density of 2.1 g/cm ³ ) were obtained.

[Comparative Example 6: Production of positive electrode active material composite (E-6) for lithium ion secondary battery]
Example except that 200 g of lithium positive electrode active material particles (B-1) was changed to 200 g of 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles B12, which was an intermediate product of Production Example 7. A positive electrode for a lithium ion secondary battery in which 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles are supported on the surface of NCM-based composite oxide secondary particles (A) in the same manner as in 1. Active material composite (E-6) (average particle size 13 μm, thickness of supporting layer of 0.5Li ₂ MnO ₃ -0.5LiMn _0.33 Co _0.33 Ni _0.33 O ₂ particles: 1.5 μm, tap density 1.9 g/ cm ³ ) was obtained.

[Comparative Example 7: Production of positive electrode active material composite for lithium ion secondary battery (E-7)]
300 g of lithium composite oxide secondary particles (A-1), 300 g of lithium composite oxide secondary particles (A-2) obtained in Production Example 2, 200 g of lithium positive electrode active material particles (B-1), Lithium cobalt oxide particles were supported on the surface of NCA-based composite oxide secondary particles (A) in the same manner as in Example 1, except that 200 g of lithium cobalt oxide particles B2, which was an intermediate product in Production Example 3, was changed. A positive electrode active material composite (E-7) for a lithium ion secondary battery (average particle size: 14 μm, thickness of supporting layer of lithium cobalt oxide particles: 2 μm, tap density: 2.8 g/cm ³ ) was obtained.

[Comparative Example 8: Production of positive electrode active material composite for lithium ion secondary battery (E-8)]
NCM-based composite oxide secondary particles were prepared in the same manner as in Example 1, except that 300 g of lithium composite oxide secondary particles (A-1) were changed to 490 g, and 200 g of lithium positive electrode active material particles (B-1) were changed to 10 g. Lithium cobalt oxide particles (B) are supported on the surface of the particles (A), and a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium cobalt oxide particles (B). Positive electrode active material composite (E-8) for lithium ion secondary batteries (average particle size 10.5 μm, lithium cobalt oxide with a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ supported on the surface) A supporting layer of particles (B) had a thickness of 200 nm and a tap density of 2.6 g/cm ³ ).

[Comparative Example 9: Production of positive electrode active material composite for lithium ion secondary battery (E-9)]
NCM-based composite oxide secondary particles were prepared in the same manner as in Example 1, except that 300 g of lithium composite oxide secondary particles (A-1) were changed to 200 g, and 200 g of lithium positive electrode active material particles (B-1) were changed to 300 g. Lithium cobalt oxide particles (B) are supported on the surface of the particles (A), and a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ is supported on the surface of the lithium cobalt oxide particles (B). Positive electrode active material composite (E-9) for lithium ion secondary batteries (lithium cobalt oxide particles having an average particle size of 18 μm and carrying a lithium-based solid electrolyte Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ on the surface) The thickness of the supporting layer of B) was 4 μm and the tap density was 2.8 g/cm ³ ).

《Evaluation of discharge capacity and rate characteristics》
All of the positive electrode active material composites for lithium ion secondary batteries obtained in Examples 1 to 11 and Comparative Examples 1 to 9 were used as positive electrode materials to produce positive electrodes for lithium ion secondary batteries. Specifically, each of the obtained positive electrode active material composites for lithium ion secondary batteries, Ketjenblack, and polyvinylidene fluoride were mixed at a mass ratio of 90:5:5, and N-methyl-2 - Pyrrolidone was added and thoroughly kneaded to prepare a positive electrode slurry. The positive electrode slurry was applied to a current collector made of aluminum foil with a thickness of 20 μm using a coating machine, and vacuum-dried at 80° C. for 12 hours. Thereafter, it was punched out into a disk shape of φ14 mm and pressed using a hand press at 16 MPa for 2 minutes to obtain a positive electrode.
Next, a coin-type secondary battery was constructed using the above positive electrode. A lithium foil punched to a diameter of 15 mm was used as the negative electrode. The electrolytic solution was prepared by dissolving LiPF ₆ at a concentration of 1 mol/L in a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 3:7. A porous polymer film was used as the separator. These battery parts were assembled and housed in an atmosphere with a dew point of −50° C. or lower by a conventional method to obtain a coin-type secondary battery (CR-2032).
A charge/discharge test was conducted using the obtained secondary battery. Specifically, after constant current charging with a current of 34 mA/g and a voltage of 4.25 V, constant current discharge with a current of 34 mA/g and a final voltage of 3.0 V is performed, and the discharge capacity at a current density of 34 mA/g (0.2 C) is determined. I asked for it. Further, constant current charging was performed under the same conditions, and constant current discharge was performed at a current density of 510 mA/g and a final voltage of 3.0 V, and the discharge capacity at a current density of 510 mA/g (3C) was determined. Note that all charge/discharge tests were conducted at 30°C. The results are shown in Table 1.
Furthermore, the discharge capacity ratio (%) was determined from the obtained discharge capacity using the following formula (8). The results are shown in Table 1.
Discharge capacity ratio (%) = (discharge capacity at 3C)/
(Discharge capacity at 0.2C) x 100 (8)

《Measurement of adsorbed water content》
All of the positive electrode active material composites for lithium ion secondary batteries obtained in Examples 1 to 11 and Comparative Examples 1 to 9 were allowed to stand for one day in an environment with a temperature of 20°C and a relative humidity of 50% to reach equilibrium. The temperature was raised to 150°C and held for 20 minutes, and then the temperature was further raised to 250°C and held for 20 minutes.The starting point was when the temperature had finished rising to 250°C. The amount of moisture volatilized during the end point of constant temperature at ℃ was measured using a Karl Fischer moisture meter (MKC-610, manufactured by Kyoto Denshi Kogyo Co., Ltd.). The measurement results are shown in Table 1.

From the results in Table 1, it can be seen that all Examples had good discharge capacity and rate characteristics (discharge capacity ratio), and the amount of water adsorption in the positive electrode active material composite was effectively reduced.
On the other hand, it can be seen that in the comparative example, at least one of discharge capacity and rate characteristics is inferior to the example. In addition, the amount of water adsorption of the positive electrode active material composites was mostly inferior to that of the Examples.
From the above, it can be seen that the positive electrode active material composite for lithium ion secondary batteries of the present invention has excellent discharge capacity and rate characteristics. Furthermore, since the amount of water adsorption is reduced, the positive electrode active material composite for lithium ion secondary batteries of the present invention has good performance in terms of durability-related properties such as cycle characteristics. I understand.

Claims (6)

The following formula (1) or formula (2):
_LiNia Co _b Mn _c M ¹ _w O ₂ ...(1)
(In formula (1), M ¹ is Mg, Ti, Nb, Fe, Cr, Si, Al, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Represents one or more elements selected from Bi and Ge. a, b, c, and w are 0.3≦a<1, 0<b≦0.7, 0<c≦0.7, Indicates a number that satisfies 0≦w≦0.3 and 3a+3b+3c+(valence of ^M1 )×w=3.)
LiNi _d Co _e Al _f M ² _x O ₂ ...(2)
(In formula (2), ^M2 is Mg, Ti, Nb, Fe, Cr, Si, Ga, V, Zn, Cu, Sr, Mo, Zr, Sn, Ta, W, La, Ce, Pb, Bi, and Represents one or more elements selected from Ge. d, e, f, x are 0.4≦d<1, 0<e≦0.6, 0<f≦0.3, 0≦ Indicates a number that satisfies x≦0.3 and 3d+3e+3f+(valence of ^M2 )×x=3.)
On the surface of lithium composite oxide secondary particles (A) consisting of lithium composite oxide particles represented by the following formula (3), formula (4), formula (5), or formula (6):
^LiM3gCohO2 _{... (} 3 ₎
(In formula (3), M ³ represents one or more elements selected from Ni, Mn, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, and Si. 3) In, g and h indicate numbers that satisfy 0≦g≦0.1, 0<h≦1, and (valence of M ³ )×g+3h=3.)
LiM ⁴ _i Mn _j O ₄ ...(4)
(In formula (4), M ⁴ represents one or more elements selected from Ni, Co, Al, Mg, Ti, V, Cr, Fe, Zr, Ga, Cu, and Si. In formula (4), i and j represent numbers satisfying 0≦i≦0.1, 0<j≦2, and (valence of ^M4 )×i+(valence of Mn)×j=7 .)
_{LiNikMn1 - kO4} ...( ₅ )
(In formula (5), k represents a number satisfying 0.3≦k≦0.7.)
_Li2MnO3 ^-LiM6O2 _... ( ₆ )
(In formula (6), M ⁶ is Ni, Mn, Co, Al, Fe, Cr, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce. (Indicates one or more elements selected from.)
A positive electrode active for a lithium ion secondary battery , in which lithium positive electrode active material particles (B) represented by: A material complex,
The mass ratio between the content of lithium composite oxide secondary particles (A) and the total content of lithium positive electrode active material particles (B) and lithium-based solid electrolyte (C) ((A):(B)+(C) )) is 95:5 to 50:50, a positive electrode active material composite for a lithium ion secondary battery. The mass ratio ((B):(C)) of the content of the lithium positive electrode active material particles (B) and the content of the lithium-based solid electrolyte (C) is 99.5:0.5 to 85:15. The positive electrode active material composite for a lithium ion secondary battery according to claim 1 . The lithium ion secondary according to claim 1 or 2 , wherein the lithium-based solid electrolyte (C) is one or more of Li ₃ PO ₄ -Li ₄ SiO ₄ and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ . Cathode active material composite for batteries. The positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 3 , having an average particle size of 2 μm to 30 μm. Next steps (I) to (III):
(I) After preparing a slurry (a-1) containing the lithium positive electrode active material particles (B) and the raw material compound of the lithium-based solid electrolyte (C) and having a solid content concentration of 20% to 65% by mass, hot air The ratio (G/S) of supply amount G (L/min) of slurry (a-1) to supply amount S (L/min) of slurry (a-1) is 500 to 10,000 to obtain granules (a). The process of obtaining
(II) The obtained granules (a) are fired at 500°C to 800°C for 10 minutes to 3 hours, and the lithium positive electrode active material particles (B ), and (III) obtaining a pre-granulated product (b) with a porosity of 45% to 80% by volume, and (III) obtaining a pre-granulated product (b) and lithium composite oxide secondary particles (A ) while applying compressive force and shearing force to crush the pre-granulated material (b), and produce lithium positive electrode active material particles (B) having a lithium-based solid electrolyte (C) supported on the surface. ) and lithium composite oxide secondary particles (A), the method for producing a positive electrode active material composite for a lithium ion secondary battery according to any one of claims 1 to 4 . The method for producing a positive electrode active material composite for a lithium ion secondary battery according to claim 5 , wherein the granules (a) obtained in step (I) have a particle size of 5 μm to 25 μm.